Sliding interfaces are common aspects of nearly all mechanical assemblies and devices, where maintenance free, low friction and low wear operation of solid lubricants are ideal, if not required. These critical interfaces are typically subjected to extreme environments, wide margins of operating temperatures, and simple water/oxygen and expected to operate predictably. The materials featured in these studies are well established (Molybdenum Disulfide [MoS₂]; Diamond-like Carbon [DLC]) yet many fundamental questions, especially those related to aging, remain within the community. This talk will explore environmental factors influencing mechano-chemical surface interactions during sliding and how microstructural differences can alter their behavior. The role of microstructure in degradation mechanisms related to performance in MoS₂ films under terrestrial (water, oxygen) and low-earth-orbit (LEO; atomic oxygen) contaminants will be discussed, alongside simulations exploring sensitivities to temperature and humidity. Preliminary studies on environmental sensitivities of DLC films, as well as novel synthesis methods will also be presented.

This work was funded by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under Contract DE-NA0003525. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.